DE102017208917A1 - High-frequency amplifier arrangement and method for designing a high-frequency amplifier arrangement - Google Patents

Abstract

A high frequency amplifier arrangement (1)
a. an amplifier part (2) having an output (100) with two output terminals (101, 102)
b. a balun (7) having an input (105) with two input terminals (106, 107) and an output (110) with two output terminals (111, 112), wherein
i. in each case an output terminal (101, 102) of the amplifier part (2) is connected to an input terminal (106, 107) of the balancing transformer (7),
ii. an output terminal (112) of the balancing transformer (7) is connected to earth,
iii. an output terminal (111) of the balancing transformer (7) can be connected to a load,
iv. between the one input terminal (106) of the balancing transformer (7) and ground, a first capacitor (44) is provided,
v. a second capacitance (45) is provided between the second input terminal (107) of the balancing transformer (7) and ground, wherein the first capacitance (44) is not equal to the second capacitance (45).

Description

The invention relates to a high-frequency amplifier arrangement. Furthermore, the invention relates to a method for designing a high-frequency amplifier arrangement.

When operating high-frequency generators often results in an increased proportion of harmonic components in the output signal, so a reduction in spectral purity. This can be highly undesirable in particular given the high demands on measurement accuracy and process stability of plasma processes.

The object of the present invention is to provide a high-frequency amplifier arrangement in which these disadvantages do not occur.

1. a. Verstärkerteil, das einen Ausgang mit zwei Ausgangsanschlüssen aufweist,
2. b. einem Symmetrierübertrager, der einen Eingang mit zwei Eingangsanschlüssen und einen Ausgang mit zwei Ausgangsanschlüssen aufweist, wobei
   1. i. jeweils ein Ausgangsanschluss des Verstärkerteils mit einem EIngangsanschluss des Symmetrierübertragers verbunden ist,
   2. ii. ein Ausgangsanschluss des Symmetrierübertragers mit Masse verbunden ist,
   3. iii. ein Ausgangsanschluss des Symmetrierübertragers mit einer Last verbindbar ist,
   4. iv. zwischen dem einen Eingangsanschluss des Symmetrierübertragers und Masse eine erste Kapazität vorgesehen ist,
   5. v. zwischen dem zweiten Eingangsanschluss des Symmetrierübertragers und Masse eine zweite Kapazität vorgesehen ist, wobei die erste Kapazität ungleich der zweiten Kapazität ist.

This object is achieved according to the invention by a high-frequency amplifier arrangement with a

1. a. Amplifier section having an output with two output terminals,
2. b. a balancing transformer having an input with two input terminals and an output with two output terminals, wherein
   1. i. in each case an output terminal of the amplifier part is connected to an input terminal of the balancing transformer,
   2. ii. an output terminal of the balancing transformer is connected to ground,
   3. iii. an output terminal of the balancing transformer is connectable to a load,
   4. iv. between the one input terminal of the balancing transformer and ground a first capacitance is provided,
   5. v. a second capacitance is provided between the second input terminal of the balancing transformer and ground, wherein the first capacitance is not equal to the second capacitance.

Symmetric transformers (English: Balanced / Unbalanced, BalUn) are often used for the conversion between a balanced line system and a single-ended line system. A symmetrical line system, for example, the line system at the output terminals of the amplifier part, because here both terminals are symmetrical with respect to a reference potential, here in particular with respect to ground. An unbalanced line system is, for example, the line system at the output terminals of the balun because one terminal is connected to a fixed reference potential, in this case in particular ground, and the other terminal can or should have a voltage which changes with respect to this fixed reference potential. Symmetrierübertrager can be used at the output of an amplifier part of a high-frequency amplifier arrangement. It has been recognized that a balun can have unbalanced parasitic components. In particular, it may have unbalanced parasitic capacitances. It was further recognized that these reduce the common mode rejection and thus the quality of the transformer. It was further recognized that the use of such Symmetrierübertragern in high-frequency generators, this provides for an increased proportion of harmonic components in the output signal, so a reduction in spectral purity.

It has been recognized that the parasitic capacitances from input terminal to output terminal of the balun may even be equal in value, and yet due to different phase relationships of the input terminals to the output terminals, there are different voltage ratios over these same capacitance values. This leads to a different current flow over these parasitic capacitances. Thus, the impedances at the input terminals to ground appear different, although the parasitic capacitances are measured individually measured. In order to equalize the impedances, it is provided according to the invention that the capacitances which are connected to the balancing transformer are asymmetrical, that is to say the first capacitance is not the same as the second capacitance.

With the aid of an asymmetrical placement, i. Unequal capacitances, can achieve a very broadband compensation of the parasitic components and greatly increase the common mode rejection. When Symmetrierübertragern in the output network of a high-frequency amplifier arrangement, capacitors are thus used at ground level at the inputs of the Symmetrierübertragers to adjust the impedances of the feeding elements. Contrary to the general understanding, these capacities are not carried out with the same but with specifically different values. The impedances visible on the feeding elements of the amplifier part become identical by this modification. This is true for both harmonic purity and other undesirable effects such as oscillations, e.g. in case of mismatch, and uneven heating of the active components of advantage.

The first capacitance and the second capacitance may differ depending on the transmission ratio of the balancing transformer. The transmission ratio of Symmetrierübertragers can thus be considered to dimension the capacity.

The balun transformer may have a primary winding connected to the two input terminals and a secondary winding connected to the two output terminals. The balancing transformer can be used for galvanic isolation.

The output terminal of the Symmetrierübertragers, which is connected to ground, can be particularly low inductively connected to ground. Also, the behavior of the Symmetrierübertragers can be improved.

The connection of the first and / or second capacitance may be connected to ground in a particularly low-inductance manner. Also, the behavior of the Symmetrierübertragers can be improved.

The connection of the first and / or second capacitance to the terminals of the Symmetrierübertragers can be particularly short and in particular low inductance connected to ground. Also, the behavior of the Symmetrierübertragers can be improved.

• • besonders breite Leiterbahnen (breiter als 5 mm)
• • eine Vielzahl von Durchkontaktierungen (mehr als zwei), die in einer Reihe oder in einer Fläche angeordnet sind
• • besonders kurze Verbindung, insbesondere kann das Verhältnis von Länge zu Breite der Verbindung kleiner 100, insbesondere kleiner 10, bevorzugt kleiner 3 sein.

A particularly low-inductive compound can be achieved by one or more of the following measures:

• • particularly wide strip conductors (wider than 5 mm)
• • a plurality of vias (more than two) arranged in a row or in a surface
• • particularly short connection, in particular, the ratio of length to width of the connection can be smaller 100 , especially smaller 10 , preferably smaller 3 be.

The first capacitance and the second capacitance may differ depending on a parasitic capacitance of the balancing transformer between the input terminals and the output terminals of the balun and / or to the ground. The parasitic capacitances of the balun can first be determined and then taken into account for the design of the first and second capacitance.

The difference between the first capacitance and the second capacitance may have a proportional proportion to the product of a parasitic capacitance of the balancing transformer, in particular between an input terminal and an output terminal of the balun and / or to ground, and the transmission ratio of the balun. For example, the first capacitance may have a capacitance value C0 and the second capacitance may have a capacitance value C0 ± parasitic capacitance x transmission ratio.

The first and / or second capacitance may comprise a discrete capacitor. In particular, the first and / or second capacitance may be designed as a discrete capacitor.

Alternatively or additionally, it is conceivable that the first and / or the second capacitance are at least partially formed as a conductor track, which is spaced from another conductor track or surface, in particular ground plane, wherein the conductor track can be part of the primary winding in particular. In this case, it may be possible to dispense with discrete capacitors.

Different first and second capacitances can be realized, for example, in that the width of the interconnect associated with the first capacitance and the width of the interconnect associated with the second capacitance differ at least in sections. It is also conceivable to realize the first and / or second capacitance in that the conductor track assigned to the primary winding of the balun transformer is embodied in sections with different widths.

Alternatively or additionally, it is conceivable that the conductor track assigned to the first capacitance has a different distance to a ground plate than the conductor track assigned to the second capacitance. Also in this way different capacity values for the first and second capacity can be realized. The first and second capacitances can also be adjusted via the distance between the primary winding and the secondary winding of the balun transformer.

The Symmetrierübertrager can be realized on a printed circuit board in planar technology. In this case, it makes sense to form the capacitances by means of tracks.

The amplifier part may comprise two transistors, one transistor each being connected to an output terminal of the amplifier part. By using different capacitances at the inputs of the balun transformer thus the impedances of the feeding transistors of the amplifier part can be adjusted. The transistors may in particular be LDMOS transistors. The transistors can be designed as identically constructed, in particular as identical transistors. The transistors may be connected at their control terminals to a signal transmitter.

The amplifier part can be designed as a push-pull amplifier, in particular in one of the operating modes Class F or Class F ^-1 .

The amplifier part can be designed as a push-pull amplifier, in particular in one of the operating modes Class A, Class B, Class AB or Class C.

1. a. Festlegen eines ersten Kapazitätswerts für eine erste Kapazität zwischen einem Eingangsanschluss des Symmetrierübertragers und Masse,
2. b. Festlegen eines zweiten Kapazitätswerts für eine zweite Kapazität zwischen dem anderen Eingangsanschluss des Symmetrierübertragers und Masse, der sich von dem ersten Kapazitätswert unterscheidet.

The scope of the invention also includes a method for designing a high-frequency amplifier arrangement having a balun transformer connected to an amplifier section, which has an input with two input connections and an output with two output connections, with the method steps:

1. a. Establishing a first capacitance value for a first capacitance between an input terminal of the balun and ground,
2. b. Establishing a second capacitance value for a second capacitance between the other input terminal of the balun and ground that differs from the first capacitance value.

Thus, the capacitances at the inputs of the balancing transformer can be adjusted as a function of detected parasitic capacitances of the balancing transformer. By this measure, the common-mode suppression of the Symmetrierübertragers and thus the harmonic purity of the output signal can be improved. In addition, unwanted effects such as oscillation and uneven heating of active components can be reduced or prevented.

A parasitic capacitance of the balancing transformer can be determined, in particular a parasitic capacitance between an input terminal and an output terminal and / or ground. The difference of the capacitance values of the first and second capacitances may be set or selected taking into account the parasitic capacitance.

The capacitance value of the second capacitance can be set or selected taking into account the transmission ratio of the balancing transformer. The second capacitance may be set to be different from the transfer ratio and parasitic capacitance of the balun or a quantity proportional thereto from the first capacitance. In particular, the second capacity may be greater or less than the first capacity by the amount of the product of transmission ratio and parasitic capacitance.

It may be determined or selected depending on whether the winding sense of the turns of the primary winding and the secondary winding of the balancing transformer is in the same direction or in opposite directions, whether the second capacitance is greater or smaller than the first capacitance. In particular, the magnitude of the product of the transmission ratio and the parasitic capacitance of the balun may be added to or subtracted from the capacitance value of the first capacitance, depending on whether the winding sense of the windings is in the same direction or in opposite directions, in order to arrive at the capacitance value of the second capacitance.

• • einem Verstärkerteil, das einen Ausgang mit zwei Ausgangsanschlüssen aufweist
• • einem Symmetrierübertrager, der einen Eingang mit zwei Eingangsanschlüssen und einen Ausgang mit zwei Ausgangsanschlüssen aufweist, wobei
  • ◯ jeweils ein Ausgangsanschluss des Verstärkerteils mit einem Eingangsanschluss des Symmetrierübertragers verbunden ist,
  • ◯ ein Ausgangsanschluss des Symmetrierübertragers mit Masse verbunden ist,
  • ◯ ein Ausgangsanschluss des Symmetrierübertragers mit einer Last verbindbar ist,
  • ◯ zwischen dem einen Eingangsanschluss des Symmetrierübertragers und Masse eine erste Kapazität vorgesehen ist,
  • ◯ zwischen dem zweiten Eingangsanschluss des Symmetrierübertragers und Masse eine zweite Kapazität vorgesehen ist, wobei die erste Kapazität ungleich der zweiten Kapazität ist,

wobei die Hochfrequenzverstärkeranordnung in einem Frequenzbereich von 1 MHz bis 160 MHz betrieben wird.The invention further relates to a method for operating a high-frequency amplifier arrangement with

• • an amplifier section that has an output with two output terminals
• A balancing transformer having an input with two input terminals and an output with two output terminals, wherein
  • ◯ in each case an output terminal of the amplifier part is connected to an input terminal of the balancing transformer,
  • ◯ an output terminal of the balancing transformer is connected to ground,
  • ◯ an output terminal of the balancing transformer is connectable to a load,
  • ◯ a first capacitance is provided between the one input terminal of the balancing transformer and ground,
  • ◯ a second capacitance is provided between the second input terminal of the balancing transformer and ground, wherein the first capacitance is not equal to the second capacitance,

wherein the high frequency amplifier arrangement is operated in a frequency range of 1 MHz to 160 MHz.

In particular, the high-frequency amplifier arrangement can be operated in a frequency range> 3 MHz, preferably> 20 MHz, particularly preferably ≥ 40 MHz. Alternatively or additionally, the high-frequency amplifier arrangement can be operated in a frequency range ≦ 80 MHz, in particular ≦ 60 MHz.

In operation, the frequency at which the radio frequency amplifier arrangement is operated can be changed. In particular, the frequency can be changed in a range of + - 20% of a center frequency. This will cause the impedances that occur at the feeding switching elements are visible, approximated. Ideally they become identical.

Further features and advantages of the invention will become apparent from the following description of embodiments of the invention, with reference to the figures of the drawing, which shows essential to the invention, and from the claims. The features shown there are not necessarily to scale and presented in such a way that the features of the invention can be made clearly visible. The various features may be implemented individually for themselves or for a plurality of combinations in variants of the invention.

In the schematic drawing embodiments of the invention are illustrated and explained in more detail in the following description.

• 1 eine schematische Darstellung einer Hochfrequenzverstärkeranordnung;
• 2 eine schematische Explosionsdarstellung eines Symmetrieübertragers, der in Planartechnik aufgebaut ist;
• 3a ein Diagramm zur Darstellung des Phasenverlaufs bei einem Symmetrieübertrager, der symmetrische Kapazitäten an seinen Eingangsanschlüssen aufweist;
• 3b einen Phasenverlauf für einen Symmetrieübertrager, der mit ungleichen Kapazitäten an seinen Eingangsanschlüssen betrieben wird;
• 4 ein Flussdiagramm zur Erläuterung des erfindungsgemäßen Verfahrens.

Show it:

• 1 a schematic representation of a high-frequency amplifier arrangement;
• 2 a schematic exploded view of a Symmetrieübertragers, which is constructed in planar technology;
• 3a a diagram showing the phase characteristic in a balun having symmetric capacitances at its input terminals;
• 3b a phase characteristic for a balun that operates with dissimilar capacitances at its input terminals;
• 4 a flowchart for explaining the method according to the invention.

The 1 shows a high-frequency amplifier arrangement 1 with an amplifier part 2 that has an exit 100 with two output connections 101 . 102 having. To the output terminals 101 . 102 are the input terminals 106 . 107 an entrance 105 a Symmetrieübertragers 7 connected. The symmetry transformer 7 also has an output 110 with output connections 111 . 112 on. The output terminal 112 is in mass 8th connected. To the output terminal 111 can be connected to a load, not shown here, in particular a plasma load.

The primary winding 6 of the power transformer 7 has a center tap 37 on that for DC supply of switching elements S1 . S2 serves. At the center tap 37 is a network 38 connected, which may have an inductance and / or a capacitor. In particular, a series connection of a capacitor and an inductor can be provided. Alternatively, a capacitance to ground and a series inductance could be provided.

The amplifier part 2 has switching elements S1 . S2 , which are formed in this case as transistors, in particular as LDMOS transistors on. The source connections of the switching elements S1 . S2 are each a capacitor 32 . 33 connected to ground. The switching elements are activated S1 . S2 via a signal transmitter 10 ,

The symmetry transformer 7 is thus connected on the input side to a symmetrical line system and on the output side to an asymmetrical line system.

The input terminals 105 . 106 of the balun 7 , which is a primary winding 6 and a secondary winding 4 have over capacities 44 . 45 with mass 8th connected. The first capacity 44 is unlike the second capacity 45 , By the first and second capacity 44 . 45 can be the impedances that the balun transformer 7 for the switching elements S1 . S2 represents, be tuned ("tuned"). Usually the first and the second capacity 44 . 45 symmetrically assumed, since both switching elements S1 . S2 should see the same load. According to the invention, however, different capacities 44 . 45 provided, as has been shown that the behavior of the Symmetrierübertragers 7 is significantly improved. This can be explained by the fact that the effects that cause parasitic capacitances can be at least partially compensated or eliminated. The parasitic capacitances occur, for example, between the input and output terminals 106 . 111 and 107 . 112 on. they are in the 1 marked as C _para .

The capacities 44 . 45 may be at least partially discrete capacitors 44 ' . 45 ' ( 2 ) be formed. However, it is also conceivable, the first and second capacity 44 . 45 at least partially form by traces, which are spaced from a ground plane. This is particularly suitable for a planar construction of the balun 7 at. Such a structure is in the 2 shown in a very schematic way. Here it can be seen that the conductor track 4 ' the secondary winding 4 of the balun 7 not just a different number of turns than the primary winding 6 but that the conductor track 6 ' the secondary winding 6 has a smaller width at least in one area than in other areas. This measure allows the capacities 44 . 45 be set.

The capacities 44 . 45 are thus at least partially through the tracks 6 ' . 4 ' through which the primary winding 6 and the secondary winding 4 are constructed, realized. In particular, the capacitance value of the first and second capacitance 44 . 45 by the width of the tracks and the distance of the tracks to a ground plane 50 result. By a suitable choice of the board insulation material, in particular by the dielectric constant of the material, the capacitance can also be influenced. The capacities 44 . 45 are in the immediate vicinity of the secondary winding 4 and primary winding 6 arranged. This means that the side length or the diameter of the areal extent of the secondary winding 4 and primary winding 6 is greater than the distance from the terminals 111 . 112 . 106 . 107 the secondary winding 4 and primary winding 6 to the capacitors 44 ' . 45 ' ,

The 3a shows a diagram in which the phase curve 150 between the output terminal 111 and input connection 106 and the phase history 151 between the output terminal 111 and the input terminal 107 as well as the phase difference 153 are shown. The phase curves are shown over the frequency f. In the example shown, symmetrical first and second capacitances, ie first and second capacitances having the same capacitance value, were used. For measurements at the points m1 to m6 one adjusts m1 a phase difference of 207 °, at m2 a phase difference of 201 °, at m3 a phase difference of 197 ° at m4 a phase difference of 194 °, at m5 a phase difference of 192 ° and at m6 a phase difference of 191 ° fixed. These values are away from the ideal value of 180 degrees.

The 3b shows the phase progressions 150 . 151 and the phase difference of 153 in the event that at the entrances 106 . 107 capacities 44 . 45 with different capacity values. at m1 Therefore, you set a phase difference of 180 °, at m2 from 181 °, at m3 from 181 °, at m4 from 182 °, at m5 from 182 ° and at m6 of 183 °. These values are much closer to the ideal phase difference of 180 °. The effects of the parasitic capacitances C _para were thus largely compensated.

The 4 shows a flowchart for explaining the method according to the invention. In a first step 200 becomes a parasitic capacitance of a balun 7 determines, in particular, the parasitic capacitance between an input terminal and an output terminal and / or between an input terminal and ground or an output terminal and ground.

In step 201 For example, a capacitance value for a first capacitance is established between an input terminal of the balun and ground.

In step 202 For example, a second capacitance value for a second capacitance between another input terminal of the balance transformer and ground is determined, which differs from the first capacitance value, taking into account the parasitic capacitance.

The step 202 may include that the capacitance value of the second capacitance is determined taking into account the transmission ratio of the balun. For example, the first capacity as C0 be set, where C0 can be influenced by the impedance requirements of the amplifier part. The second capacity can then be set as C0 + Coffset, where Coffset = transmission ratio × parasitic capacitance. If the sense of winding of the primary and the secondary winding of the balun transformer is opposite, then the sign of Coffset can turn around. In this case, the second capacity is C0 - Coffset. Alternatively, the first and the second capacitance can be positioned at the respective other input terminal of the balun.

Claims (14)

High frequency amplifier arrangement (1) with a a. Amplifier part (2) having an output (100) with two output terminals (101, 102) b. a balun (7) having an input (105) with two input terminals (106, 107) and an output (110) with two output terminals (111, 112), wherein i. in each case an output terminal (101, 102) of the amplifier part (2) is connected to an input terminal (106, 107) of the balancing transformer (7), ii. an output terminal (112) of the balancing transformer (7) is connected to earth, iii. an output terminal (111) of the balancing transformer (7) can be connected to a load, iv. between the one input terminal (106) of the balancing transformer (7) and ground, a first capacitor (44) is provided, v. a second capacitance (45) is provided between the second input terminal (107) of the balancing transformer (7) and ground (8), wherein the first capacitance (44) is not equal to the second capacitance (45). High frequency amplifier arrangement according to Claim 1 , characterized in that the first capacitance (44) and the second capacitance (45) differ in dependence on the transmission ratio of the balancing transformer (7). High-frequency amplifier arrangement according to one of the preceding claims, characterized in that the balancing transformer (7) has a primary winding (6) connected to the two Input terminals (106, 107) is connected, and a secondary winding (4), which is connected to the two output terminals (111, 112). High-frequency amplifier arrangement according to one of the preceding claims, characterized in that the output terminal (112) of the Symmetrierübertragers (7), which is connected to ground (8), is particularly low inductively connected to ground (8). High-frequency amplifier arrangement according to one of the preceding claims, characterized in that the first capacitor (44) and the second capacitor (45) in dependence on a parasitic capacitance of the Symmetrierübertragers (7) between the input terminals (106, 107) and the output terminals (111, 112) of the Symmetrierübertragers (7) and / or to the mass (8) differ. High-frequency amplifier arrangement according to one of the preceding claims, characterized in that the difference between the first capacitance (44) and second capacitance (45) is a proportional proportion to the product of a parasitic capacitance of the balun (7), in particular between an input terminal (106, 107 ) and an output terminal (111, 112) of the Symmetrierübertragers (7) and / or to the ground (8), and the transmission ratio of the Symmetrierübertragers (7). High-frequency amplifier arrangement according to one of the preceding claims, characterized in that the first and / or the second capacitance (44, 45) at least partially as a conductor track which is spaced from another conductor track or surface, in particular ground surface, are formed, wherein the conductor track in particular Part of the primary winding (8) can be. High frequency amplifier arrangement according to Claim 7 , characterized in that the width of the conductor track assigned to the first capacitance (44) and the width of the conductor track assigned to the second capacitance (45) differ. High frequency amplifier arrangement according to Claim 7 or 8th , characterized in that the conductor track assigned to the first capacitance (44) has a different distance to a ground plate (50) than the conductor track assigned to the second capacitance. High-frequency amplifier arrangement according to one of the preceding claims, characterized in that the balancing transformer (7) is realized on a printed circuit board in planar technology. High-frequency amplifier arrangement according to one of the preceding claims, characterized in that the amplifier part (2) comprises two transistors (S1, S2), wherein in each case one transistor (S1, S2) is connected to an output terminal (101, 102) of the amplifier part (2). High-frequency amplifier arrangement according to one of the preceding claims, characterized in that the amplifier part (2) is designed as a push-pull amplifier, in particular in one of the following operating modes Class F or Class F ^-1 . Method for designing a high-frequency amplifier arrangement (1) having a balun transformer (7) connected to an amplifier section (2), having an input (105), two input terminals (106, 107) and one output (110), with two output terminals (111, 112), with the method steps: a. Determining a parasitic capacitance of the balancing transformer (7), b. Establishing a first capacitance value for a first capacitance (44) between an input terminal (106) of the balancing transformer (7) and ground (8), c. Establishing a second capacitance value (45) between the other input terminal (107) of the balun (7) and ground (8) different from the first capacitance value. Method for operating a high-frequency amplifier arrangement (1) with a a. Amplifier part (2) having an output (100) with two output terminals (101, 102) b. a balun (7) having an input (105) with two input terminals (106, 107) and an output (110) with two output terminals (111, 112), wherein i. in each case an output terminal (101, 102) of the amplifier part (2) is connected to an input terminal (106, 107) of the balancing transformer (7), ii. an output terminal (112) of the balancing transformer (7) is connected to earth, iii. an output terminal (111) of the balancing transformer (7) can be connected to a load, iv. between the one input terminal (106) of the balancing transformer (7) and ground, a first capacitor (44) is provided, v. a second capacitor (45) is provided between the second input terminal (107) of the balancing transformer (7) and earth, wherein the first capacitor (44) is not equal to the second capacitor (45), the high frequency amplifier arrangement (1) being in a frequency range of 1 MHz to 160 MHz is operated.

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